The most widely used transparent conducting thin films, Indium-Tin-Oxide (ITO), will surly encounter difficulties for Indium is naturally limited and its price rising fast very year. Searching for Indium free transparent conducting oxides (TCO) becomes one of the important issues in this field. Among of which, ZnO:Al (AZO) is the most import candidate and is used, now, in photovoltaic industry. In the future, flexible substrates are necessary, therefore, to preventing degrading of TCO crystal by repeatedly bending, TCO should be produced in amorphous or nano-crystal types. By properly doping of Ti in ZnO lattice, a certain form of amorphous-nanocrystal mixture films can be obtained at room temperature. Unfortunately, amorphous or nano-crystal with poor crystal structure suppress the electric conduction. Growth films at few hundred degrees may enhance the crystallization, however, the flexible substrate, such as PET, can only sustained temperature lower than 150oC. In this project, an UV assisted film growth technique is used to study the effect of the UV assistant growth on films properties. The aim of this study is wish to grow films with better crystallization at lower growth temperature.
Physical properties of films are investigated by the transmittance spectroscopy (N&K analyzer), X-ray dffractometer (XRD) and atomic force microscopy (AFM). It is found that the optical band gap increases and shows an obvious blue shifting due to the short range order in the present films. All films exhibits high level of transparency in the visible range. The grazing angle incident X-ray diffraction (GID XRD) indicates that high ratio of amorphous phase for films grown at high working gas pressure and low RF power. For certain growth conditions, pure amorphous films can be obtained. Oppositely, films grown at low working gas pressure and high RF power manifest crystal growth along all directions resulting shifting and broadening in XRD peaks. Higher the Ti doping levels higher the amorphous ratio. By gown films at higher temperatures, (002) peak dominates the GID XRD measurements. It is found that the 266nm UV assisted growth enhances crystallization and roughness of films at relatively low temperature, lower than the highest sustainable temperature of PET.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0823111-172752 |
| Date | 23 August 2011 |
| Creators | Cheng, Yu-chi |
| Contributors | Hua Shu Hsu, Jau-Wern Chiou, Hsiung Chou, Shih-Jye Sun |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0823111-172752 |
| Rights | user_define, Copyright information available at source archive |
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